Along with advancements in the digital image techniques, advancements are being made in a technique for compression-encoding image data so as to correspond to an increasing amount of data. With the improvement in data processing capability, a complicated operation for the compression encoding is possible, and the compression ratio of the image data is being greatly increased. Specifically, as a compression encoding technique which is employed in satellite and terrestrial digital HDTV broadcasting, a compression encoding scheme called MPEG2 (Moving Picture Experts Group 2) is used. In addition, MPEG4 AVC/H.264 (hereinafter, referred to as “H.264/AVC”), which is one of the compression encoding schemes which have been standardized following MPEG2, has a compression ratio which is even more improved than MPEG2.
In order to perform the compression encoding at high speed, there has been proposed a method in which the encoding is performed in parallel by the use of a plurality of encoding units. For example, in the technique disclosed in JP-A-2002-199392, an image plane is divided into a plurality of regions, and the divided regions are respectively encoded in parallel. In the technique disclosed in JP-A-2008-66851, the encoding is performed in parallel with GOP units by using a closed GOP (closed Group Of Pictures) structure.